The purpose of ACTG 226 is to determine the pharmacokinetics, maximum tolerated dose and long-term safety of oral ganciclovir in HIV-infected infants, children and adolescents with CMV infection or quiescent CMV disease. This is a Phase I, dose-escalating, long-term tolerance study of oral ganciclovir. It is designed to evaluate the pharmacokinetics and to determine the MTD of oral ganciclovir. The study will primarily determine pharmacokinetic parameters of the oral suspension of ganciclovir. Data on the capsule formulation for older children and adolescents will also be obtained at the maximum tolerated dose.